Lubricated pump rod string for oil wells

ABSTRACT

A tool for incorporation into the production tubing of an oil well to enable the pump rod string to reciprocate in a lightweight oil or other lubricant, and the heavy oil being produced flowing in the annulus between the production tube and casing. The tool includes a pressure operated circulating sub, a pump rod pack-off sub and a tubing pack-off sub, as well as a rod pack-off retrieving tool and a back pressure gas production sub which replaces the usual bottom standing valve in the pump. This tool enables the oil being produced to be pumped up through the annulus between the tubing and casing with the tubing above the tool being filled with a light fluid, such as diesel oil, water, or any other similar light fluid which will lubricate the pump rod.

United States Patent [191 [111 3,765,482

Harrison Oct. 16, 1973 LUBRICATED PUMP ROD STRING FOR OIL Primary Examiner-James A. Leppink WELLS Attorney-Harvey B. Jacobson et al. [75] Inventor: Sidney L. Harrison, Chickasha,

Okla [57] ABSTRACT A tool for incorporation into the production tubing of Asslgneei Heavy Producers Service an oil well to enable the pump rod string to reciprocorporated, Chickasha, Okla.

cate in a lightweight oil or other lubricant, and the heavy oil being produced flowing in the annulus between the production tube and casing. The tool includes a pressure operated circulating sub, a pump rod pack-off sub and a tubing pack-off sub, as well as a rod pack-off retrieving tool and a back pressure gas production sub which replaces the usual bottom standing valve in the pump. This tool enables the oil being produced to be pumped up through the annulus between the tubing and casing with the tubing above the tool beingfilled with a light fluid, such as diesel oil, water, or any other similar light fluid which will lubricate the pump rod.

10 Claims, 2 Drawing Figures LUBRICATED PUMP ROD STRING FOR OIL WELLS BACKGROUND OF THE INVENTION duction tubing is disposed concentrically within a casing with the lower end of the tubing having a pump operated by an elongated pump rod string disposed within the production tubing. Reciprocation of the pump rod string operates the pump and the oil being produced is pumped upwardly through the production tubing in a well known manner. Frequently, the oil being produced is quite thick or heavy which creates a substantial frictional drag on the pump rod string and, in many instances, causes the pump rod string to bend or flex at several points along its length during the downstroke and then straighten out on the upstroke thus, in effect, shortening the pump rod string. This bending or flexing of the pump rod string causes the rods making up the string to break and damage both the rods and tubing at each contact point. The bending and flexing or compression of the pump rod string results in a shorter operating stroke of the pump and the frictional resistance of the heavy oil being produced and the frictional contact between the pump rod string and the tubing at a plurality of points slows down the operation of the pump and materially reduces the strokes per minute of the pump, thereby reducing the volume of oil being produced.

SUMMARY OF THE INVENTION An object of the invention is to provide a tool that is inserted into the production tubing when the tubing is being made-up which bypasses the heavy oil being produced into the annulus between the tubing and casing with a tubing pack-off enabling the tubing above the pack-off to be filled with a light lubricating fluid which reduces the frictional resistance of the pump rod string during reciprocation thereof, effectively lubricates the same and eliminates the bending and flexing of the pump rod string during reciprocation thereof.

Another object of the invention is to provide a tool in accordance with the preceding object incorporating a retrieving tool for the rod pack-off sub which enables the pump rodstring and rod pack-off sub to be pulled out of the tubing for replacement of the rod pack-off sub or for any other purpose without the necessity of pulling the tubing and pump.

A further object of the invention is to provide a tool in accordance with the preceding objects in which a circulating sub is incorporated including a piston assembly retained in position by a shear pin which enables recovery of the lightweight fluid by pressuring the I piston assembly sufficient to shear the pin.

Still another object of the invention is to provide a tool in accordance with the preceding objects in which a series of ball and check valve assemblies are provided below the rod pack-off sub which takes the place of the bottom standing valve in the pump and removes the hydrostatic pressure from the ball and seat in the pump plunger which eliminates gas lock of the pump and also fluid pounding to provide longer life for the pump and rod string.

Yet another significant object of the present invention is to provide a tool for incorporation into the production tubing of an oil well which is quite simple in .construction, easy to make-up with the production tubing, effective to increase the pump strokes and reduce frictional wear and relatively inexpensive to maintain and operate.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an oil well illustrating diagramatically the components of the 'oil well and the disposition of the present invention therein.

FIG. 2 is 'a vertical, sectional view, on an enlarged scale, of the tool of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now specifically to the drawings, the-tool of the present invention is generally designated by reference numeral 10 and is incorporated into the production tubing '12 oriented concentrically in a casing 14 with the pump rod string 16 disposed within the production tubing 12 in a conventional manner and connected with a conventional pump 18 oriented in the production zone of the oil well illustrated in FIG. 1 in a well known manner. Suitable mechanism (not shown) is provided for reciprocating the pump rod string 16 for operating the pump 18 and suitable valves may be provided for the production tubing 12 and the upper end of the casing 14, as illustrated in FIG. 1.

The tool 10 includes an upper tubing 20 that includes external threads 22 for connection withthe production tubing and a lower tubing 24 having external threads 26 for connection with the pump barrel or a section of production tubing that is connected with the pump barrelzThe lower end of the upper tubing 22 is externally threaded at 28 and the upper end of the lower tubing 24 is externally threaded at 30 with the threaded ends 28 and 30 being interconnected by a tubing pack-off sub generally designated by the numeral 32, which includes an upper tubing 34 internally threaded as at 36 for threaded engagement with the lower threaded end 28 of the upper tubing 20. The tubing 34 is internally threaded as at 38 at its lower end for receiving an adapter 40 that is externally threaded at 42 at its upper end and internally threaded at 44 at its lower end with the-internally threaded end 44 engaging the threaded upper end 30 of the lower tubing 24 and the externally threaded upper end 42 in threaded engagement with the internally threaded lower end 38 of the tubing 34, thus fonning the tubing pack-ofi sub with annular packing members 46 being received between the upper end of the adapter 40 and a shoulder 48 defined by an annular recess 50 extending from the bottom end of the tubular member 34 to a 'point adjacent the internally threaded upper end portion 36. All of the aforementioned components are threaded so as the production tubing is being made-up, these components will be incorporated therein.

Disposed interiorly of the upper tubing 20 and the tubing pack-off sub 32 is a pump rod pack-off sub 52 which includes a tubing 54 having an inwardly extending peripheral shoulder 56 at the upper end thereof defining a shoulder for engaging the uppermost of a plurality of rod packing rings 58. The lower end of the tubular member 54 is internally threaded at 60 for screwthreadedly receiving the upper externally threaded portion 62 of the lower rod pack-off member 64 which enwith the internal threads being righthanded and the extemal threads being lefthanded and larger or coarser than the internal threads. The external threads which are left-handed engage corresponding internal lefthanded threads in the inner upper end portion 42 of the adapter 40 or lower half of the tubing pack-off sub 32. The internal threads at 66 on the lower half of the rod pack-off sub designated by numeral 64 corresponds with and can be threadedly engaged by an externally threaded upper end portion 68 of a rod pack-off retrieving tool 70. The pack-off retrieving tool 70 is internally threaded at the upper end 72 thereof for screwthreaded engagement with the threaded lower end 74 of the pump rod 16. Correspondingly, the lower end of the rod pack-off retrieving tool 70 is internally threaded at 76 for screw-threaded engagement with the theaded upper end 78 of the pump plunger rod 80 which extends to the pump plunger 18 in a well known manner.

The lower tubing 24 is provided with a back pressure gas production sub generally designated by the numeral 82 and which includes a plurality of circumferentially and longitudinally spaced projections 84 integral with the tubing 24 with each projection including a longitudinally extending hollow area or passageway 86 therein freely receiving a movable ball valve 88. The upper end portion of each hollow area or passageway 86 is provided with a longitudinally extending slot 90 which communicates with the annulus 92 between the casing 14 and production tubing 12. The lower end ,of each hollow area or passageway 86 is communicated with the interior of the tubing 24 through an opening-94,. Each hollow area or passageway 86 is provided with a horizontally disposed annular valve seat 96 in the lower portion thereof above the inlet opening 94 for coaction withthe ball valve 88 to form a check valve to enable flow of heavy oil from the interior of the lower tubing 24 out through the openings 94, up through the valve seats 96 and out through the slots 90 during the upward stroke of the pump plunger with the ball valves 88 seating on the valve seats 96 and preventing return flow during the downward stroke of the pump plunger, thereby eliminating the hydrostatic pressure of the oil being pumped by the pump and forming a standing valve which replaces the normally provided bottom standing valve in the pump. This structure also eliminates gas lock of the pump and reduces or eliminates the fluid pounding which can occur when the pump plunger ball and seat supports a hydrostatic head when the oil level in the pump barrel is below the plunger so that the plunger will move rapidly until it engages the oil in the barrel which results in considerable pounding that can result in excessive wear and damage to the pump.

In normal operation, the production tubing, pump, tool and pump rod string are all made up at the surface and oriented in the casing in a well known manner with a pack-off 98 being disposed between the tubing 12 and the casing 14 above the producing zone but below the tool was illustrated in FIG. 1. In normal operating condition, the pump rod 16 reciprocates thus operating the pump in the normal manner and when in this condition, the rod pack-off retrieving tool 70 is spaced from the rod pack-off sub 52 sincethe upper limit of the movement of the retrieving tool 70 is below the lower end of the rod pack-off sub 52. The heavy oil pumped by the pump, passes out through the openings 94 and 90 into the annulus 92 since the pump rod 16 is packed off by the rod pack-off sub 52. In order to lubricate the pump rod string 16 in the production tubing 12, the

production tubing 12 is filled with a light fluid, such as diesel oil, water, or the like, which reduces wear and friction between the pump rod string and tubing. This lightweight fluid does not become mixed with the oil being pumped in view of the rod pack-off sub 52 and is retained in the annular space between the pump rod string 16 and the production tubing 12 and can be recovered through a pressure operated circulating sub 100 incorporated into the upper tubing 20 in a manner described hereinafter.

When it is desired to remove the rod pack-off sub 52 for repair or replacement or to remove the pump.

plunger, it is only necessary to lift the pump rod string 16 upwardly until the threaded upper end 68 of the retrieving tool 70 engages the internal threads on the lower end portion 16 of the rod pack-off sub 52. Thepump r'od string 16 is then rotated in a righthand direction, thus threading the retrieving tool 70 into the lower end of the rod pack-off sub 52. As soon as the retrieving tool 70 is fully threaded into the rod pack-off sub 52, the rod pack-off sub 52 will be rotated so that the lefthanded threads on the exterior of the lower end of the rod pack-off sub 52 will become disengaged from the internal lefthanded threads on the lower end portion of the tubing pack-off sub 32 thereby disconnecting the rod pack-off sub from the tubing pack-off sub and enabling the rod pack-off sub to be removed without pulling the production tubing and pump from the wall. Reinstallation of the rod pack-off sub is, of course, accomplished by reversing the procedure outlined above. Thus, the rod-pack-off sub that contains the packing 58 for the polished rod can-be retrieved along with the pump plunger so as to eliminate the necessity-of pulling the tubing when replacing the packing 58 or the pump plunger.

The circulating sub includes a protuberance 102 having a passageway 104 at the lower end thereof communicating with the interior of the upper tubing 20 at a point above the rod pack-off sub. A piston 106 with an O-ring seal 108 on the lower end thereof is slidably disposed in the interior of the protuberance 102 for longitudinal movement in a cylindrical bore 100 from a position adjacent the opening 104 to a position above an opening 112. The piston 106 is retained in positon by a nut 114 rigid with the protuberance 102 and a shear pin 116 extending through the nut and the upper end of the piston rod to retain the piston in position so that fluid will not flow out through the opening 104 and opening 112. If, for any reason, it is desired to recover or remove the lubricant above the rod pack-off 52 pressure exerted on the fluid within the production tubing above the rod pack-off sub will break the shear pin 116 and move the piston 106 upwardly to enable the light fluid to be discharged into the annulus between the tubing and casing and recovered at the surface. A projection 118 is provided above the piston and protruberance to protect it during insertion and removal of the tool and production tubing.

In actual practice, the pressure circulating sub 100 may be oriented at any point above the rod pack-off sub, but usually not more than to feed above the rod pack-off sub. Also, the normal operating stroke of the pump rod string will normally position the retrieving tool 70 several feet below the rod pack-off sub at the upper limit of its reciprocatory movement. All of the components may be constructed of readily available materials normally employed in the construction of oil well components and the surfaces on all of the projections may be rounded or appropriately inclined to eliminate sharp or severe edges.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

I. A tool for use in an oil well of the type having a casing, a production tubing disposed concentrically within the casing, a reciprocating-type pump in the lower portion of the tubing, a pump rod string reciprocal in the tubing for operating the pump, said tool comprising a tubing assembly incorporated into the produc tion tubing and including a pump rod pack-off sub, means releasably securing the rod pack-off sub to the tubing assembly, and a retrieving tool incorporated in the pump rod for engaging the removing the pump rod pack-off sub from the tubing assembly and production tubing without pulling the production tubing from the casing.

2. The structure as defined in claim 1, wherein said tubing assembly includes a production sub disposed below the rod pack-ofi sub and above a pack-off disposed between the casing and tubing, said production sub including passage means communicating the production tubing with the annulus between the production tubing and casing, check valve means closing the passage means during downward reciprocation of the pump plunger and automatically opening the passage means during upward movement of the pump plunger.

3. The structure as defined in claim 2, together with a quantity of lightweight fluid disposed in the production tubing above the rod pack-off sub for lubricating the pump rod during reciprocation thereof.

4. The structure as defined in claim 3, together with a circulating sub for the lubricating fluid for circulating the fluid out through the tubing into the annulus between the tubing and casing for recovery thereof at the surface, said circulating sub including a pressureoperated valve means openable in response to a predetermined pressure being exerted on the lubricating fluid for opening the valve means and circulating the lubricating fluid outwardly into the annulus between the tubing and easing.

5. The structure as defined in claim 2, wherein said tubing assembly includes a tubing pack-off sub incorporated therein for engaging the rod pack-off sub in sealed relation, said tubing pack-off sub and said rod pack-off sub having a threaded connection adjacent the lower end thereof to enable disengagement of the rod pack-off sub from the tubing pack-off sub when the retrieving tool engages the rod pack-off sub and the pump rod, retrieving tool and rod pack-off sub are rotated to unthread the rod pack-off sub from the tubing pack-off sub, thus enabling pulling of the rod pack-off sub and pump plunger from the production tubing without pulling the tubing and pump.

6. The structure as defined in claim 5, together with a quantity of lightweight fluid disposed in the production tubing above the rod pack-off sub for lubricating the pump rod during reciprocation thereof, a circulating sub for the lubricating fluid for circulating the fluid out through the tubing into the annulus between the tubing and casing for recovery thereof at the surface, said circulating sub including a pressure-operated valve sure being exerted on the lubricating fluid for opening the valve means and circulating the lubricating fluid outwardly into the annulus between the tubing and casmg.

7. The structure as defined in claim 1, wherein said tubing assembly includes a tubing pack-off sub incorporated therein for engaging the rod pack-off sub in sealed relation, said tubing pack-off sub and said rod pack'off sub having a threaded connection adjacent the lower end thereof to enable disengagement of the rod pack-off sub, from the tubing pack-off sub when the retrieving tool engages the rod pack-off sub and the pump rod, retrieving tool and rod pack-off sub are to tated to unthread the rod pack-off sub from the tubing pack-off sub, thus enabling pulling of the rod pack-off sub and pump plunger from the production tubing without pulling the tubing and pump.

8. In combination with an oil well of the type having a casing, a production tubing disposed concentrically within the casing to define an annulus therebetween, a pump in the lower portion of the tubing for producing upward flow of produced oil in the production tubing, a pump rod inthe tubing for operating the pump, a packer between the tubing and casing above the pump 'to packoff the annulus, a tool incorporated into the production tubing above the packer and including a tubing assembly, a pump rod pack-off sub within the tubing assembly to prevent upward flow of produced oil in the production tubing thereabove, means releasably securing the pump rod pack-off sub in the tubing assembly, means incorporated in the pump rod for engaging and removing the pump rod pack-off sub from the tubing assembly and production tubing without pulling the production tubing from the casing, a production sub disposed below the pump rod pack-off sub and above the packer disposed between the casing and tubing, said production sub including passage means communicating the production tubing with the annulus between the production tubing and casing whereby produced oil is pumped into the annulus between the production tubing and casing, check valve means opening the passage means when upward flow of produced out through the tubing into the annulus between the tubing and casing for recovery thereof at the surface, said circulating sub including a pressure-operated valve means openable in response to a predetermined pressure being exerted on the lubricating fluid for opening 7 the valve means and circulating the lubricating fluid I outwardly into the annulus between the tubing and cas- 

1. A tool for use in an oil well of the type having a casing, a production tubing disposed concentrically within the casing, a reciprocating-type pump in the lower portion of the tubing, a pump rod string reciprocal in the tubing for operating the pump, said tool comprising a tubing assembly incorporated into the production tubing and including a pump rod pack-off sub, means releasably securing the rod pack-off sub to the tubing assembly, and a retrieving tool incorporated in the pump rod for engaging and removing the pump rod pack-off sub from the tubing assembly and production tubing without pulling the production tubing from the casing.
 2. The structure as defined in claim 1, wherein said tubing assembly includes a production sub disposed below the rod pack-off sub and above a pack-off disposed between the casing and tubing, said production sub including passage means communicating the production tubing with the annulus between the production tubing and casing, check valve means closing the passage means during downward reciprocation of the pump plunger and automatically opening the passage means during upward movement of the pump plunger.
 3. The structure as defined in claim 2, together with a quantity of lightweight fluid disposed in the production tubing above the rod pack-off sub for lubricating the pump rod during reciprocation thereof.
 4. The structure as defined in claim 3, together with a circulating sub for the lubricating fluid for circulating the fluid out through the tubing into the annulus between the tubing and casing for recovery thereof at the surface, said circulating sub including a pressure-operated valve means openable in response to a predetermined pressure being exerted on the lubricating fluid for opening the valve means and circulating the lubricating fluid outwardly into the annulus between the tubing and casing.
 5. The structure as defined in claim 2, wherein said tubing assembly includes a tubing pack-off sub incorporated therein for engaging the rod pack-off sub in sealed relation, said tubing pack-off sub and said rod pack-off sub having a threaded connection adjacent the lower end thereof to enable disengagement of the rod pack-off sub from the tubing pack-off sub when the retrieving tool engages the rod pack-off sub and the pump rod, retrieving tool and rod pack-off sub are rotated to unthread the rod pack-off sub from the tubing pack-off sub, thus enabling pulling of the rod pack-off sub and pump plunger from the production tubing without pulling the tubing and pump.
 6. The structure as defined in claim 5, together with a quantity of lightweight fluid disposed in the production tubing above the rod pack-off sub for lubricating the pump rod during reciprocation thereof, a circulating sub for the lubricating fluid for circulating the fluid out through the tubing into the annulus between the tubing and casing for recovery thereof at the surface, said circulating sub including a pressure-operated valve means openable in response to a predetermined pressure being exerted on the lubricating fluid for opening the valve means and circulating the lubricating fluid outwardly into the annulus between the tubing and casing.
 7. The structure as defined in claim 1, wherein said tubing assembly includes a tubing pack-off sub incorporated therein for engaging the rod pack-off sub in sealed relation, said tubing pack-off sub and said rod pack-off sub having a threaded connection adjacent the lower end thereof to enable disengagement of the rod pack-off sub from the tubing pack-off sub when the retrieving tool engages the rod pack-off sub and the pump rod, retrieving tool and rod pack-off sub are rotated to unthread the rod pack-off sub from the tubing pack-off sub, thus enabling pulling of the rod pack-off sub and pump plunger from the production tubing without pulling the tubing and pump.
 8. In combination with an oil well of the type having a casing, a production tubing disposed concentrically within the casing to define an annulus therebetween, a pump in the lower portion of the tubing for producing upward flow of produced oil in the production tubing, a pump rod in the tubing for operating the pump, a packer between the tubing and casing above the pump to pack-off the annulus, a tool incorporated into the production tubing above the packer and including a tubing assembly, a pump rod pack-off sub within the tubing assembly to prevent upward flow of produced oil in the production tubing thereabove, means releasably securing the pump rod pack-off sub in the tubing assembly, means incorporated in the pump rod for engaging and removing the pump rod pack-off sub from the tubing assembly and production tubing without pulling the production tubing from the casing, a production sub disposed below the pump rod pack-off sub and above the packer disposed between the casing and tubing, said production sub including passage means communicating the production tubing with the annulus between the production tubing and casing whereby produced oil is pumped into the annulus between the production tubing and casing, check valve means opening the passage means when upward flow of produced oil is caused by the pump and automatically opening the passage means when produced oil is not flowing upwardly.
 9. The combination as defined in claim 8, together with a quantity of lightweight fluid disposed in the production tubing above the rod pack-off sub for lubricating the pump rod during movement thereof.
 10. The combination as defined in claim 8, a circulating sub for the lubricating fluid for circulating the fluid out through the tubing into the annulus between the tubing and casing for recovery thereof at the surface, said circulating sub including a pressure-operated valve means openable in response to a predetermined pressure being exerted on the lubricating fluid for opening the valve means and circulating the lubricating fluid outwardly into the annulus between the tubing and casing. 